From e9e06ca627d328fb67771949e36924f73b0067c9 Mon Sep 17 00:00:00 2001
From: Douwe Maan <douwe@selenight.nl>
Date: Mon, 20 Jun 2016 19:17:56 +0200
Subject: [PATCH] Add Gitlab::Diff::LineMapper
---
lib/gitlab/diff/line_mapper.rb | 64 +++++++++++
spec/lib/gitlab/diff/line_mapper_spec.rb | 137 +++++++++++++++++++++++
2 files changed, 201 insertions(+)
create mode 100644 lib/gitlab/diff/line_mapper.rb
create mode 100644 spec/lib/gitlab/diff/line_mapper_spec.rb
diff --git a/lib/gitlab/diff/line_mapper.rb b/lib/gitlab/diff/line_mapper.rb
new file mode 100644
index 00000000000..bde5b4eedaa
--- /dev/null
+++ b/lib/gitlab/diff/line_mapper.rb
@@ -0,0 +1,64 @@
+# When provided a diff for a specific file, maps old line numbers to new line
+# numbers and back, to find out where a specific line in a file was moved by the
+# changes.
+module Gitlab
+ module Diff
+ class LineMapper
+ attr_accessor :diff_file
+
+ def initialize(diff_file)
+ @diff_file = diff_file
+ end
+
+ # Find new line number for old line number.
+ def old_to_new(old_line)
+ map_line_number(old_line, from: :old_line, to: :new_line)
+ end
+
+ # Find old line number for new line number.
+ def new_to_old(new_line)
+ map_line_number(new_line, from: :new_line, to: :old_line)
+ end
+
+ private
+
+ def diff_lines
+ @diff_lines ||= @diff_file.diff_lines
+ end
+
+ # Find old line number based on new line number.
+ def map_line_number(from_line, from:, to:)
+ # If no diff file could be found, the file wasn't changed, and the
+ # mapped line number is the same as the specified line number.
+ return from_line unless diff_file
+
+ # To find the mapped line number for the specified line number,
+ # we need to find:
+ # - The diff line with that exact line number, if it is in the diff context
+ # - The first diff line with a higher line number, if it falls between diff contexts
+ # - The last known diff line, if it falls after the last diff context
+ diff_line = diff_lines.find do |diff_line|
+ diff_from_line = diff_line.send(from)
+ diff_from_line && diff_from_line >= from_line
+ end
+ diff_line ||= diff_lines.last
+
+ # If no diff line could be found, the file wasn't changed, and the
+ # mapped line number is the same as the specified line number.
+ return from_line unless diff_line
+
+ diff_from_line = diff_line.send(from)
+ diff_to_line = diff_line.send(to)
+
+ # If the line was removed, there is no mapped line number.
+ return unless diff_to_line
+
+ # Because we may not have the diff line with the exact line number
+ # we were looking for, we need to adjust the mapped line number.
+ distance = diff_from_line - from_line
+
+ diff_to_line - distance
+ end
+ end
+ end
+end
diff --git a/spec/lib/gitlab/diff/line_mapper_spec.rb b/spec/lib/gitlab/diff/line_mapper_spec.rb
new file mode 100644
index 00000000000..4e50e03bb7e
--- /dev/null
+++ b/spec/lib/gitlab/diff/line_mapper_spec.rb
@@ -0,0 +1,137 @@
+require 'spec_helper'
+
+describe Gitlab::Diff::LineMapper, lib: true do
+ include RepoHelpers
+
+ let(:project) { create(:project) }
+ let(:repository) { project.repository }
+ let(:commit) { project.commit(sample_commit.id) }
+ let(:diffs) { commit.diffs }
+ let(:diff) { diffs.first }
+ let(:diff_file) { Gitlab::Diff::File.new(diff, diff_refs: commit.diff_refs, repository: repository) }
+ subject { described_class.new(diff_file) }
+
+ describe '#old_to_new' do
+ context "with a diff file" do
+ let(:mapping) do
+ {
+ 1 => 1,
+ 2 => 2,
+ 3 => 3,
+ 4 => 4,
+ 5 => 5,
+ 6 => 6,
+ 7 => 7,
+ 8 => 8,
+ 9 => nil,
+ # nil => 9,
+ 10 => 10,
+ 11 => 11,
+ 12 => 12,
+ 13 => nil,
+ 14 => nil,
+ # nil => 15,
+ # nil => 16,
+ # nil => 17,
+ # nil => 18,
+ # nil => 19,
+ # nil => 20,
+ 15 => 21,
+ 16 => 22,
+ 17 => 23,
+ 18 => 24,
+ 19 => 25,
+ 20 => 26,
+ 21 => 27,
+ # nil => 28,
+ 22 => 29,
+ 23 => 30,
+ 24 => 31,
+ 25 => 32,
+ 26 => 33,
+ 27 => 34,
+ 28 => 35,
+ 29 => 36,
+ 30 => 37
+ }
+ end
+
+ it 'returns the new line number for the old line number' do
+ mapping.each do |old_line, new_line|
+ expect(subject.old_to_new(old_line)).to eq(new_line)
+ end
+ end
+ end
+
+ context "without a diff file" do
+ let(:diff_file) { nil }
+
+ it "returns the same line number" do
+ expect(subject.old_to_new(100)).to eq(100)
+ end
+ end
+ end
+
+ describe '#new_to_old' do
+ context "with a diff file" do
+ let(:mapping) do
+ {
+ 1 => 1,
+ 2 => 2,
+ 3 => 3,
+ 4 => 4,
+ 5 => 5,
+ 6 => 6,
+ 7 => 7,
+ 8 => 8,
+ # nil => 9,
+ 9 => nil,
+ 10 => 10,
+ 11 => 11,
+ 12 => 12,
+ # nil => 13,
+ # nil => 14,
+ 13 => nil,
+ 14 => nil,
+ 15 => nil,
+ 16 => nil,
+ 17 => nil,
+ 18 => nil,
+ 19 => nil,
+ 20 => nil,
+ 21 => 15,
+ 22 => 16,
+ 23 => 17,
+ 24 => 18,
+ 25 => 19,
+ 26 => 20,
+ 27 => 21,
+ 28 => nil,
+ 29 => 22,
+ 30 => 23,
+ 31 => 24,
+ 32 => 25,
+ 33 => 26,
+ 34 => 27,
+ 35 => 28,
+ 36 => 29,
+ 37 => 30
+ }
+ end
+
+ it 'returns the old line number for the new line number' do
+ mapping.each do |new_line, old_line|
+ expect(subject.new_to_old(new_line)).to eq(old_line)
+ end
+ end
+ end
+
+ context "without a diff file" do
+ let(:diff_file) { nil }
+
+ it "returns the same line number" do
+ expect(subject.new_to_old(100)).to eq(100)
+ end
+ end
+ end
+end
--
GitLab